On the Miscibility of Nematic Liquid Crystals with Ionic Liquids and Joint Reaction for High Helical Twisting Power Product(s)

Mixtures of nematic liquid crystals (LCs) with chiral ionic liquids (CILs) may find application as active materials for electrically driven broadband mirrors. Five nematic liquid crystal hosts were mixed with twenty three ionic liquids, including chiral ones, and studied in terms of their miscibility within the nematic phase. Phase diagrams of the mixtures with CILs which exhibited twisted nematic phase were determined. Miscibility, at levels between 2 and 5 wt%, was found in six mixtures with cyanobiphenyl-based liquid crystal host—E7. On the other hand, the highest changes in the isotropization temperature was found in the mixtures with isothiocyanate-based liquid crystal host—1825. Occurrence of chemical reactions was found. A novel chiral binaphtyl-based organic salt [N11116][BNDP] was synthesized and, in reaction to the 1825 host, resulted in high helical twisting power product(s). Selectivity of the reaction with the isothiocyanate-based liquid crystal was found.


Introduction
Electrically induced broadening of the reflection band was presented in liquid crystal (LC) mixtures with chiral ionic liquids (CILs) [1,2]. Thus, they are candidates for application in electrically switchable mirrors and transflective displays, e.g., e-TransFlector™, developed by Kent Optronics. The LC + CIL mixtures might be advantageous with respect to the widely-studied Polymer Stabilized Cholesteric Liquid Crystals [3][4][5][6] in terms of lower energy consumption in this application.
A miscibility of CILs with LCs within the nematic phase, besides sufficiently high helical twisting power (HTP) of the chiral dopant, seems to be the most crucial parameter for these applications. Such mixtures have already been studied in the literature [1,2,[7][8][9][10][11][12], mainly with respect to their electrically induced effects. In our recent paper [9], chiral ionic compounds, formed by mesogenic chiral phenylpyridine derivative and strong organic acids, were miscible, to some extent, with the nematic LC host. The papers from Akagi group [7,8] describe miscibility of nematic ionic liquid crystals with chiral dopants and, alternatively, with a salt composed of binaphtyl-based chiral counter-ions, obtaining, in both cases, twisted nematic phase with use of chiral ionic species, which makes these mixtures potentially applicable. More examples of ionic liquid crystals forming the nematic phase by themselves are described in refs. [13][14][15][16][17][18][19]. However, these examples should be treated as exceptions to the rule because lamellar smectic or columnar phases are preferred in most ionic liquid crystals [20], which, in turn, are not likely to mix with nematic LCs [21].
Based on literature, the solubility of ILs increases in various environments because of such factors as: hydrophilicity of each of the ions of ILs [22,23], presence of Coulomb

Ionic Liquids
The following ILs were used for the miscibility studies with the LCs. Non-chiral ILs of nos. 1-10, and CILs of nos. 11 and 12 are presented in Figure 2. The following CILs of nos. 13-23 in Figure 2 were synthesized by our team. CILs with menthoxymethyl substituent(s) (Men) and various ammonium groups: imidazolium [36][37][38][39], pyridinium [40], and alkylammonium [41] groups (nos. 13-21 in  For the estimation of water content in ionic liquids, the Mid-IR absorption spectra in the 4000-400 cm −1 range were recorded, with the use of ATR FT-IR accessory. Absorption at the arbitrarily chosen wavenumber 3450 cm −1 of the water absorption band was chosen. Direct values from the ATR measurements after subtraction of the background (minimal value in range 4000-3200 cm −1 ) were taken for rough comparison of the water content in the studied ionic liquids. Details and the Mid-IR spectra are presented in section S3.1 in the Supplementary Materials.

Studies of Miscibility, Reactivity and Helical Pitch in Mixtures of the LCs with ILs
For the miscibility and related studies, for which results are presented in Sections 3.1-3.3, the LC and the IL components were weighted at proper weight fraction and mixed in a vial on a hot-plate with the temperature set above the melting and isotropization points of both components for a time of 2 min, if not stated otherwise. For mixtures of the LCs with the CILs exhibiting a twisted nematic phase, additional sets of samples were prepared for study of the phase diagrams (in range to CIL weight fraction up to about 30%). The mixtures were enclosed between two plain cover glass microscopic slides, and the textures of the mixtures were collected under the microscope with respect to the temperature. Details of the preparation of the mixtures are described in section S1.2 in the Supplementary Materials.

Ionic Liquids
The following ILs were used for the miscibility studies with the LCs. Non-chiral ILs of nos. 1-10, and CILs of nos. 11 and 12 are presented in Figure 2. The following CILs of nos. 13-23 in Figure 2 were synthesized by our team. CILs with menthoxymethyl substituent(s) (Men) and various ammonium groups: imidazolium [36][37][38][39], pyridinium [40], and alkylammonium [41] groups (nos. 13-21 in  For the estimation of water content in ionic liquids, the Mid-IR absorption spectra in the 4000-400 cm −1 range were recorded, with the use of ATR FT-IR accessory. Absorption at the arbitrarily chosen wavenumber 3450 cm −1 of the water absorption band was chosen. Direct values from the ATR measurements after subtraction of the background (minimal value in range 4000-3200 cm −1 ) were taken for rough comparison of the water content in the studied ionic liquids. Details and the Mid-IR spectra are presented in Section S3.1 in the Supplementary Materials.

Studies of Miscibility, Reactivity and Helical Pitch in Mixtures of the LCs with ILs
For the miscibility and related studies, for which results are presented in Sections 3.1-3.3, the LC and the IL components were weighted at proper weight fraction and mixed in a vial on a hot-plate with the temperature set above the melting and isotropization points of both components for a time of 2 min, if not stated otherwise. For mixtures of the LCs with the CILs exhibiting a twisted nematic phase, additional sets of samples were prepared for study of the phase diagrams (in range to CIL weight fraction up to about 30%). The mixtures were enclosed between two plain cover glass microscopic slides, and the textures of the mixtures were collected under the microscope with respect to the temperature. Details of the preparation of the mixtures are described in Section S1.2 in the Supplementary Materials.
For the studies of reactivity between the LC and the CIL components, the mixtures exhibiting twisted nematic phase at x IL ≈ 5 wt% were heated at the hot-plate at a similar temperature to the mixture preparation for a total time of 2, 10, and 30 min. Magnitude of the shift in the isotropization temperature with the heating time was studied. Experimental details of the reactivity studies are described in Section S1.3 in the Supplementary Materials. For the studies of reactivity between the LC and the CIL components, the mixtures exhibiting twisted nematic phase at xIL ≈ 5 wt% were heated at the hot-plate at a similar temperature to the mixture preparation for a total time of 2, 10, and 30 min. Magnitude of the shift in the isotropization temperature with the heating time was studied. Experimental details of the reactivity studies are described in section S1.3 in the Supplementary Materials.
The phase transition temperatures were investigated under a polarized optical microscope, equipped with a heating/cooling stage in a crossed-polarizers setup. The number of phases in the samples was also judged macroscopically by the observation of the sample through crossed polarizers. The isotropization temperature was determined as a temperature at which no anisotropic regions were observed in the field of view (assuring no homeotropic alignment). Protocol for identification of the microscopic textures, appearing dark in crossed-polarizers setup, is described in section S1.4.1 in the Supplementary Materials. The standard uncertainty of the microscopic measurements of the phase transition temperature (u) was estimated at 1.0 °C. More experimental details of the microscopic determinations are described in section S1.4 in the Supplementary Materials.
For study of the helical pitch of the twisted nematic phase, of the mixtures exhibiting twisted nematic phase, the fingerprint (Legarde) and wedge cell (Grandjean-Cano) methods were used alternatively, depending on the type of anchoring of the twisted nematic phase The phase transition temperatures were investigated under a polarized optical microscope, equipped with a heating/cooling stage in a crossed-polarizers setup. The number of phases in the samples was also judged macroscopically by the observation of the sample through crossed polarizers. The isotropization temperature was determined as a temperature at which no anisotropic regions were observed in the field of view (assuring no homeotropic alignment). Protocol for identification of the microscopic textures, appearing dark in crossed-polarizers setup, is described in Section S1.4.1 in the Supplementary Materials. The standard uncertainty of the microscopic measurements of the phase transition temperature (u) was estimated at 1.0 • C. More experimental details of the microscopic determinations are described in Section S1.4 in the Supplementary Materials.
For study of the helical pitch of the twisted nematic phase, of the mixtures exhibiting twisted nematic phase, the fingerprint (Legarde) and wedge cell (Grandjean-Cano) methods were used alternatively, depending on the type of anchoring of the twisted nematic phase in the cells-homeotropic twisted nematic (cholesteric) and planar twisted nematic (cholesteric), respectively. The measurements by the fingerprint method were performed after cooling the mixtures from the isotropic phase before the measurement. Spectrophotometric method for helical pitch determination was used to monitor progress of the reaction of 1825 liquid crystal host with [N 11116 ][BNDP] chiral salt, described in the Section 3.4. Experimental details of the helical pitch measurements are described in Section S1.5 in the Supplementary Materials. with about 10 wt% of the dopant were prepared. The reactions were performed at temperatures of the mixture equal to 150 • C and 131 • C, which was found to be above and below the isotropization temperature of the LC host, respectively. Small portions of the reaction mixture were collected after certain periods of time after the start: 15, 30, 45, 60, 75, 105, and 170 min (or other, if stated), and the helical pitch of the twisted nematic phase was determined, as described in the previous section. A reference sample, composed of two molecules separately containing the ions of the novel chiral salt-5 wt% of [N 11116 ]Br and 5 wt% of BNDHP, was studied. Other reference samples were investigated, at slightly changed conditions, to study specificity of the reaction. Details are described in Section S1.6 in the Supplementary Materials.

Survey Studies of Miscibility of the Liquid Crystals with the Ionic Liquids
LCs of the structures depicted in Figure 1 were used as hosts in the mixtures with ILs ( Figure 2) for a study of their mutual miscibility by POM. At this stage, each of the studied ILs was doped into each of the LCs at the x IL in a range of 4.4-5.4% (with exception of some of the mixtures with ILs nos. 11 and 12-which were doped into LC hosts at a weight fraction of 20 ± 1%; detailed conditions are described in Table S3 in the Supplementary Materials). The doping level of about 5% was chosen in order to introduce sufficient helical twisting power to observe twisted nematic phase textures under the microscope. For practical use, commercial chiral dopants as CB15 (HTP ≈ 6-8 µm −1 ) [21,42] and S811/R811 (HTP ≈ 11 µm −1 ) [42] should be doped evenly at about 32% or 20%, respectively, to form selective reflection of light in the visible range.
The mixtures were characterized in terms of: (a) presence of a separate phase of the IL dopant; (b) shift in the isotropization temperature of the nematic phase of LC host (nematic-isotropic phase transition temperature) (∆T NI ) of the nematic LC host; (c) presence of the twisted nematic phase (only in case of CILs). For a rough estimation of relative water content, the ILs were characterized by absorbance value at an arbitrarily chosen wavenumber of 3450 cm −1 (A 3450cm −1 ).
All of the studied LC + IL mixtures at IL content about 5 wt%, studied by POM, were found to be biphasic. Only partial solubility of the ILs in the host nematic phase of the LC hosts were found. The isotropic or crystalline phase (depending on the IL type) co-extisted with the nematic phase of the LC hosts. Signs of miscibility of the ILs with the LC hosts were noticed: significant magnitude of the |∆T NI | and induction of the twisted nematic phase (indicated in graph in the Figure 3 by star symbols), but the only latter in case of mixtures with some of the CILs. The results of the |∆T NI |, with respect to LC and IL used, are presented in the Figure 3 and in the Table S3 in the Supplementary Materials. Chemical reactions between the LC and CIL components were considered to affect the results, and they could be an effect of self-reactivity of the ILs or their reactivity with the LC hosts.
Analyzing the results, with respect to the studied ILs, the mixtures of the LCs with nonchiral ILs nos. 1-6 and 9 introduced only low |∆T NI | values. An exception to this observation was slightly higher |∆T NI |-specifically in the case of the E7 mixtures with bromide ILs nos. 4-6. Higher |∆T NI | were observed in the studied mixtures of the LCs with the following ILs: tion with a component possessing cyanide group, which was present in this multic nent LC host at a weight fraction of 23%. Mixtures with commercial chiral lacta [C2C1Im][Lact] (IL no. 11) and [Choline][Lact] (IL no. 12), exhibited high |ΔTNI| only 1825 LC host, which might be an effect of a chemical reaction, manifested by the in the color of the mixtures and formation of gaseous products.
[   More generally, high |ΔTNI| values in mixtures of the 1825 LC host with carb ILs nos. 10-12 and 23 were expected to be caused by chemical reactions. The wat tained in the ILs may have affected the mixtures with the host 1825 because of po reactivity with isothiocyanates. However, relatively high water content, also pre ILs nos. 2, 3, and 5, did not substantially change the TNI in their mixtures with the 1 host.
All of the synthesized CILs with menthoxymethyl substituent(s) (nos. 13-21) ited significant |ΔTNI| of the mixtures with most of the studied LC hosts. The mo  Table S3 in the Supplementary Materials. The column graph below presents the parameter A 3450cm −1 , related to the water content of the ILs. Mixtures with CILs are highlighted by yellow background color. Details are described in the text.
More generally, high |∆T NI | values in mixtures of the 1825 LC host with carboxylate ILs nos. 10-12 and 23 were expected to be caused by chemical reactions. The water contained in the ILs may have affected the mixtures with the host 1825 because of potential reactivity with isothiocyanates. However, relatively high water content, also present in ILs nos. 2, 3, and 5, did not substantially change the T NI in their mixtures with the 1825 LC host.
All of the synthesized CILs with menthoxymethyl substituent(s) (nos. 13-21) exhibited significant |∆T NI | of the mixtures with most of the studied LC hosts. The most pronounced changes were found in the mixtures with: . These CIL dopants caused high |∆T NI |, even in the mixtures with the 1754 LC host, which was considered to be non-reactive. These IL dopants might have dissolved partially in the 1754 LC host or underwent a self-reaction in the reaction environment because of: high temperature, presence of air, water, or LC host.
Despite the miscibility or reactivity of some non-chiral ILs with the 1825 host, only a low |∆T NI | was found in the case of the mixtures doped with synthesized menthoxymethylbased CILs composed of fluorinated anions: [NTf 2 ] and [PFSI]. Without more extensive studies, one could only speculate that this was due to a low amount of water in these ILs, as isothiocyanate (-N=C=S) group reacts with water and alcohols. In contrast, the E7 mixtures with mentoxymethyl-based CILs often showed a relatively high |∆T NI | and induction of the twisted nematic phase, in the case of six CILs from this group.
The synthesized chiral salts with cetyltrimethylammonium cation (ILs nos. 22 and 23) exhibited high |∆T NI |-in case with naproxenium anion (IL no. 23) and relatively low |∆T NI | in case of the binaphtyl-based anion (IL no. 22). However, as it will be presented below in more detailed studies, the latter chiral salt reacts with three of the studied LC hosts forming twisted nematic phase, especially with 1825 LC host, in which high HTP product(s) were formed.
With respect to the studied LC hosts, high |∆T NI | results were the most numerously observed in the mixtures with 1825, E7, and ZLI-1496 LC hosts. The twisted nematic phase textures were observed in ten mixtures with only these three hosts, but they were the most effective in the case of the first two hosts. Figure 4 presents examples of the twisted nematic phase textures observed in the LC + CIL mixtures. The mixtures were of interest of the more detailed phase diagram and reactivity studies in the Section 3.2.
Moreover, the type of the anchoring of the nematic phase in the mixtures was studied in the plain glass cells, and the results are presented in the . Without more extensive studies, one could only speculate that this was due to a low amount of water in these ILs, as isothiocyanate (-N=C=S) group reacts with water and alcohols. In contrast, the E7 mixtures with mentoxymethyl-based CILs often showed a relatively high |ΔTNI| and induction of the twisted nematic phase, in the case of six CILs from this group.
The synthesized chiral salts with cetyltrimethylammonium cation (ILs nos. 22 and 23) exhibited high |ΔTNI|-in case with naproxenium anion (IL no. 23) and relatively low |ΔTNI| in case of the binaphtyl-based anion (IL no. 22). However, as it will be presented below in more detailed studies, the latter chiral salt reacts with three of the studied LC hosts forming twisted nematic phase, especially with 1825 LC host, in which high HTP product(s) were formed.
With respect to the studied LC hosts, high |ΔTNI| results were the most numerously observed in the mixtures with 1825, E7, and ZLI-1496 LC hosts. The twisted nematic phase textures were observed in ten mixtures with only these three hosts, but they were the most effective in the case of the first two hosts. Figure 4 presents examples of the twisted nematic phase textures observed in the LC + CIL mixtures. The mixtures were of interest of the more detailed phase diagram and reactivity studies in the Section 3.2. Moreover, the type of the anchoring of the nematic phase in the mixtures was studied in the plain glass cells, and the results are presented in the Table S3 in

Phase Diagrams and Reactivity Studies of the Mixtures Exhibiting Twisted Nematic Phase
The LC + CIL mixtures, exhibiting a twisted nematic phase (indicated by star symbols in the Figure 3), were studied with respect to weight fraction of the CIL component in range from 0 to 30%. The phase diagrams of the LC and CIL pairs are presented in Figure  5. The CILs, which are typically crystalline at the room temperature:

Phase Diagrams and Reactivity Studies of the Mixtures Exhibiting Twisted Nematic Phase
The LC + CIL mixtures, exhibiting a twisted nematic phase (indicated by star symbols in the Figure 3), were studied with respect to weight fraction of the CIL component in range from 0 to 30%. The phase diagrams of the LC and CIL pairs are presented in Figure 5 Figure S8 in the Supplementary Materials. The multicomponent LC hosts-1825 and E7-might be reactive with the ILs because of the presence of functional -N=C=S isothiocyanate, C≡C bonds, and cyanide group -C≡N. Another experiment was performed to check the reactivity of the selected mixtures. Progress of the |∆T NI | of LC + CIL mixtures with heating time was studied. The results are presented as insets in graphs in the Figure 5.
The E7 mixtures, with the CILs presented in the Figure 5, only exhibited a low change of the |∆T NI | with heating time from 2 to 30 min, indicating no or a very slow reaction. However, it could not be excluded that an instant reaction with the LC host had occurred with no further changes in the isotropization temperature in this time range. An exception found for E7 + [MenMenIm][SCN] mixture of 3.0 • C increase in T NI might be an effect of a partial evaporation of some of the E7 host components, as the T NI of a reference sample (E7 LC host) at similar heating conditions increased by 2.0 • C. Details are described in the Section S1.3 in the Supplementary Materials.
The phase diagrams of all of the mixtures presented in the Figure 5 consisted of a region from 0 up to about 5 or 10 wt%, where the decrease in the isotropization temperature was observed. Then, the phase transition temperature stabilized at the x IL up to 20 or even 30 wt%. In case of certain mixtures (Figure 5a-d,f), the T NI decreases at the step from about 20 to 30 wt%, what might be caused by higher fraction of the isotropic phase of the IL, which, in turn, may dissolve the LC molecules at respective higher level. Miscibility of the components in the twisted nematic range was found in all of these six mixtures at a level of about 2 wt% from the room temperature up to temperature 7-10 • C below the  Figure S8

Studies of the Helical Pitch of the mixtures Exhibitingthe Twisted Nematic Phase
As highlighted by star symbols in the graph in Figure 3, the twisted nematic phase was induced in ten of the mixtures of the CILs with E7, 1825, and ZLI-1496 LC hosts, but in as many as seven mixtures with the first LC host. Helical pitch of the twisted nematic phase (p) was determined alternatively by fingerprint (Legarde) or wedge cell (Grandjean-Cano) method (compared in ref. [43]), as described in the Section S1.5 in the Supplementary Materials. The fingerprint method is not the most reliable from the known methods (according to the paper [43] and its references). However, the presence of the CILs in the mixtures caused homeotropic twisted nematic alignment in the samples, limiting the choice of the methods for the helical pitch determination. The inverse pitch was calculated for comparison purposes, as it is proportional to the weight-based HTP (β w ) by relation: β w = p −1 · x IL −1 (assuming enantiomeric excess of the chiral dopant to be equal unity). The results are presented in Table 1.
[N11116][BNDP] (studied in not-dried and dried state) exhibited respectively lower |ΔTNI| values with the CIL weight fraction and are presented in Figure S8 in the Supplementary Materials. The multicomponent LC hosts-1825 and E7-might be reactive with the ILs because of the presence of functional -N=C=S isothiocyanate, C≡C bonds, and cyanide group -C≡N. Another experiment was performed to check the reactivity of the selected mixtures. Progress of the |ΔTNI| of LC + CIL mixtures with heating time was studied. The results are presented as insets in graphs in the Figure 5.   Abbreviations: N h *-fingerprint texture of the twisted nematic phase, N pl *-planar alignment of the twisted nematic phase, N h -homeotropic alignment of the nematic phase, I-isotropic liquid phase. 2 Loosely-packed fingerprint textures were observed. The measurements were performed at most tightly-packed fingers observed. 3 Occurrence of chemical reaction between the components was found, thus the results are valid only for heating time equal 2 min at the preparation conditions of the sample. 4 Observations of the mixture were performed in nematic range. The twisted nematic lines were observed, but not packed tight enough to perform the measurement (observations at 75 • C).
The twisting power may come from miscibility of the chiral components in the LC host or from potential chemical reaction between the components from which new chiral compounds might be formed. For the first six mixtures in the Table 1, the miscibility of the CIL in the LC according to the Figure 5 is between 2 and 5%, thus β w of these mixtures can be estimated at order of magnitude of several µm −1 , which is comparable with e.g., CB15-commercial chiral dopant.
The highest determined inversed helical pitch (p −1 ) was found in the mixtures with

Studies of the Reaction of the [N 11116 ][BNDP] Chiral Salt with the Multicomponent 1825 Liquid Crystal Host for High Helical Twisting Power Product(s)
High helical twisting power of the chiral dopants is still of interest among other liquid crystalline materials [21,[44][45][46][47][48], especially those with new electro-optical functionalities, such as optical tunability [44,45], an electrically tunable reflection band [47], and blue phases, which are used in systems such as electro-optical modulators [48].
The novel chiral salt [N 11116 ][BNDP] was chosen for further studies, because of introducing the highest HTP changes in mixtures with multicomponent isothiocyanate-based LC host-1825, pronounced by appearance of selective light reflection band within the NIR and visible light range after relatively long heating time.
The [N 11116 ][BNDP] chiral salt was doped to the 1825 LC host at about 10 wt%. The reaction was performed above the isotropization temperature of the liquid crystal host-at 150 • C or slightly below-at 131 • C, independently, in a presence of a small amounts of solvents. The NIR and UV-Vis transmission spectra of the mixtures, with respect to the heating time at 150 • C, are presented in Figure 6 and for heating at 131 • C-in Figure  S10a in the Supplementary Materials. Details are described in the Section S1.6 in the Supplementary Materials. aterials 2022, 15, x FOR PEER REVIEW 11 at 150 °C or slightly below-at 131 °C, independently, in a presence of a small amoun solvents. The NIR and UV-Vis transmission spectra of the mixtures, with respect t heating time at 150 °C, are presented in Figure 6 and for heating at 131 °C-in Figure  Samples doped only with 10 wt% of BNDHP acid and those without doping di exhibit any reflection band within the NIR range or twisted nematic texture unde microscope after heating (results not presented), which may have been caused by the solubility of the BNDHP compound in the 1825 host.
The transmission spectra of the sample doped with 5 wt% of BNDHP and 5 w [N11116]Br, as a function of heating time, are presented in Figure 7a. In the case of th of these two individual dopants, the reflection band also appeared within the NIR r and was shifting toward short wavelengths with the heating time. The reflection band not appear when a similar reaction was performed at a hot-plate temperature of 13 even after 75 min (results presented in Supporting Info- Figure S10b). This finding be related to the limited miscibility between components when the liquid crystal host was still in the nematic phase. The reaction mixture was not clear at 131 °C, which contrast to the result of use of the novel salt [N11116][BNDP] as the chiral dopant. Samples doped only with 10 wt% of BNDHP acid and those without doping did not exhibit any reflection band within the NIR range or twisted nematic texture under the microscope after heating (results not presented), which may have been caused by the poor solubility of the BNDHP compound in the 1825 host.
The transmission spectra of the sample doped with 5 wt% of BNDHP and 5 wt% of [N 11116 ]Br, as a function of heating time, are presented in Figure 7a. In the case of the use of these two individual dopants, the reflection band also appeared within the NIR range and was shifting toward short wavelengths with the heating time. The reflection band did not appear when a similar reaction was performed at a hot-plate temperature of 131 • C even after 75 min (results presented in Supporting Info- Figure S10b). This finding may be related to the limited miscibility between components when the liquid crystal host 1825 was still in the nematic phase. The reaction mixture was not clear at 131 • C, which is in contrast to the result of use of the novel salt [N 11116 ][BNDP] as the chiral dopant. the room temperature. Mixtures of the 1825 LC host doped with about 5 wt% of BNDHP and 5 wt% of [N11116]Br were measured one day after the preparation. The transmission spectra are presented in Figure 7b. Photographs of a selected sample within the time, ranging from 2 to 45 days after preparation, are presented in Supporting Info- Figure S11 and show, visually, the progress of the reaction with aging time, as growth of the selective reflection band region on the sample. Other reference samples, with other LC hosts-E7 and 1754-were prepared and tested for reactivity with the above single-and double-component dopants or their selfreactivity. Only low twisting power twisted nematic textures were observed by POM after 15 min of heating and remained up to 175 min, in case of E7 mixtures. The reference studies are described in more details in the section S3.5.  Other reference samples, with other LC hosts-E7 and 1754-were prepared and tested for reactivity with the above single-and double-component dopants or their self-reactivity. Only low twisting power twisted nematic textures were observed by POM after 15 min of heating and remained up to 175 min, in case of E7 mixtures. The reference studies are described in more details in the Section S3.5. Br, were r similar because of a similar order of magnitude of the induced helical twisting p Slightly delayed dynamics and higher helical twisting power were observed in the ca the double-dopant mixture. The reaction probably requires both types of ions: a) a [N (cetyltrimethyl) cation that introduces an ionic environment in the reaction mixtur long hydrocarbon chain, which may help in the solubility of the liquid crystal co nents; b) a [BNDP] anion for linking with isothiocyanate compound(s) to obtain high ical twisting power product(s). Assuming the weight fraction of the dopant (or sum dopants) the effective helical twisting power (βw,eff) (defined as βw,eff = p −1 · xw,dopants −1 ) fo highest result presented in Figure 8, would be at the level of about 34 μm −1 , which is high for chiral dopants. Potentially, separated chiral product(s) would have even h HTP. However, a quantity and number of different chiral product(s) in the reaction tures were unknown.
As a joint reaction between the two components occur, high HTP of the prod could be expected when the chiral center was transferred and linked covalently wit LC host molecules. The reaction may occurred potentially at isothiocyanate group or C≡C bond of the host LC molecules. However, formation of new chiral centers in 18 host molecules, also catalyzed by the chiral [BNDP] anion could not be neglecte known that binaphtyl-based compounds can catalyze regioselective substitution [27

Conclusions
The miscibility in the nematic phase was searched in mixtures of 5 various LC As a joint reaction between the two components occur, high HTP of the product(s) could be expected when the chiral center was transferred and linked covalently with the LC host molecules. The reaction may occurred potentially at isothiocyanate group or triple C≡C bond of the host LC molecules. However, formation of new chiral centers in 1825 LC host molecules, also catalyzed by the chiral [BNDP] anion could not be neglected, as known that binaphtyl-based compounds can catalyze regioselective substitution [27].

Conclusions
The miscibility in the nematic phase was searched in mixtures of 5 various LC hosts doped with about 5 wt% of 23 various ILs. Shift in the isotropization temperature and the appearance of the twisted nematic phase in the mixtures with CILs indicated certain level of miscibility of the LC and IL components. However, the results in certain systems might have been affected by joint reaction between the components. Most of the synthesized menthoxymethyl-based CILs caused a relatively high |∆T NI | in mixtures with various LC hosts. Twisted nematic phase was induced in some of the mixtures of E7 and 1825 LC hosts with the menthoxymethyl-based CILs and 1825, E7, and ZLI-1496 LC hosts with the novel chiral salt [N 11116 ][BNDP]. Phase diagrams of these mixtures in range of weight fraction, up to about 30%, were determined. Six mixtures of E7 LC host with menthoxymethyl CILs exhibited miscibility at the weight fraction between about 2% and 5%. For the application purposes, the limited miscibility might be overcome by increased HTPHTP of the chiral dopant. Both of the parameters should be further balanced in the design of structures of the chiral ionic dopants.
Some of these mixtures, mainly based on isothiocyanate-based LC host-1825-exhibited reactivity with IL dopants, especially those with carboxylic anions.  Table S1. Physical properties of the studied liquid crystals, used as hosts in mixtures with ionic liquids; Table S2. Details of the studied ionic liquids; Table S3